1. Field of the Invention
The present invention is generally directed to the field of manufacturing integrated circuit devices, and, more particularly, to systems and methods for dicing a wafer.
2. Description of the Related Art
The manufacturing of semiconductor devices may involve many process steps. For example, semiconductor fabrication typically involves processes such as deposition processes, etching processes, thermal growth processes, various heat treatment processes, ion implantation, photolithography, etc. Such processes may be performed in any of a variety of different combinations to produce semiconductor devices that are useful in a wide variety of applications.
Integrated circuit devices are formed in regions of a semiconducting substrate known as die. The number of die on a particular substrate depends upon the particular type of integrated circuit device and the size of the substrate. Typically, a substrate may have hundreds of die formed thereon.
After the integrated circuit devices are manufactured and tested, they must be packaged for sale. This packaging process typically involves coupling the die to another structure, such as a leadframe, so that electrical connections can be made between the die and other electrical components or devices, e.g., a printed circuit board. Packaging also typically involves encapsulating all or a portion of the die within an encapsulant material, e.g., mold compound. A vast number of techniques and structure have been and continue to be employed in packaging the vast number of integrated circuit devices on the market.
Typically, each of the individual die on a substrate are separated or singulated by cutting the substrate with a dicing saw. The saw blades used during the wafer dicing operation are typically made of diamond particles that are embedded or bonded in a metal matrix. Such saw blades are well-suited for cutting relatively hard, brittle materials, such as silicon. During dicing operations, the saw blade is rotated at a very high rate of speed, and the diamonds make small chips in the silicon substrate.
In some cases, various relatively soft materials are applied to the substrate, e.g., die attach tape attached to the backside of the substrate, protective polymeric films or layers on the active side (front side) of the substrate, etc. Typically, these layers are applied to the substrate prior to performing the saw-cutting or dicing process. In some cases, these layers of material are intended to remain in place as part of the finished product. For example, laminated layers of material may be applied to the backside of the substrate to protect the die in direct flip chip packaging applications, adhesive films may be attached for use as die attach materials, particularly in die stacking applications, and optical films may be applied to control or manage light penetration and/or reflection in optical devices, e.g., CMOS imager devices.
The chips generated during the dicing process may cause several problems. For example, the functional circuitry and structures on the die may be damaged by impact impingement with the chips or particles created during dicing operations. In later process operations, such particles or chips may be inadvertently pressed into the functional circuitry on the die. For example, this may occur in subsequent processes such as die picking, die stacking and/or encapsulation. Particles that adhere to the surface of the die may also cause the integrated circuit device to fail or underperform during later operations. For example, the particles that adhere to the surface of the die can create a stress point on the die without causing a detectable failure when the device is first made. However, over time, such a stress point may lead to fatigue failure during the operational life of the integrated circuit device. For optical devices, the presence of such particles can interfere with or prevent the transmission of light for emitting devices or they can prevent or limit the collection of light for sensing devices.
The attachment of various relatively soft films or layers to the substrate, which are subsequently cut during dicing operations, may also cause several problems. One such problem is that the saw blade may become “loaded” with such materials. Blade loading occurs when resin builds up on the surface of the blade or flows into the pores of the blade matrix. Blade loading may decrease cutting efficiency, increase blade heating, decrease blade life, increase blade breakage and/or cause an increase in chipping of the substrate. Additionally, as the blade cuts through soft polymeric material, it tends to melt that material. As the blade spins, this material may be cast off and may be deposited on the surface of the dies. Such particles may lead to functional failure or yield loss of the integrated circuit devices. For example, polymeric particulars that are deposited on wire bond pads are known to cause so-called wire bond “no sticks,” which may result in significant yield loss in semiconductor assembly operations.
While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.